The Flow Cytometry Facility is an essential resource for members of all three Research Programs of The Wistar Institute Cancer Center. Members of the Immunology Program are highly dependent on this facility for cell sorting, phenotypic and functional analysis of lymphocyte populations, and for characterization of antigen expression. Members of the other two programs rely on the facility for analysis such as apoptosis and cell cycle progression. The facility, equipped with state of the art instrumentation, offers services performed by the highly skilled flow cytometry personnel as well as investigator-performed analyses on user-operated instrumentation. The following services are provided: High quality, affordably priced single and multi-parameter analysis of biological particles from homogeneous or mixed populations; Rapid Purification of cell populations by sorting; Training and expertise to assist investigators in choosing optimized experimental conditions and reagents; Technical support for analyses of flow cytometry/cell sorting data; and Storing, archiving, and retrieving flow cytometric data.